Pump, in particular a blood pump

ABSTRACT

The present invention relates to a pump, in particular a blood pump having a proximal and a distal end and a pump housing arranged therebetween, a driveshaft arranged in an interior of the pump housing along the longitudinal direction, a conveying element arranged on the driveshaft, and a cannula. Here, the pump housing, the shaft arrangement and the conveying element are coordinated with one another in such a way that these guarantee the best possible efficiency and longevity of the pump.

The invention lies in the field of mechanics, precision mechanics andmaterial technology and relates to a pump or pump arrangement, inparticular a blood pump.

In the prior art pumps are known that have a proximal and a distal endand also a pump housing arranged therebetween, a driveshaft arranged inan interior of the pump housing along a longitudinal direction, aconveying element arranged on the driveshaft, and also a cannula or acatheter arranged proximally of the pump housing. Pumps of this typeoften have a flexible driveshaft, such that the pumps can be guided evenat locations that are difficult to access and can implement their pumpeffect there. One example is a blood pump, which for example is insertedinto the left ventricle of the heart through the femoral artery via theaortic arch and remains in the region of the aortic valve. At theproximal end of the pump, i.e. for example at the end of the driveshaftthat remains arranged outside the body, the pump may be connected to amotor, which drives the driveshaft and thus the conveying elementarranged on the driveshaft, which is now arranged for example in theleft ventricle. Blood can thus be pumped from the ventricle into theaorta.

In such pumps it is also known that the pump housing is formed in such away that it can be transferred at least in part into the cannula or thecatheter under application of a force acting at the proximal end of thepump. In other words, by means of the application for example of atensile force in the region of the proximal end of the driveshaft, thepump housing can be drawn into the cannula and can thus be brought froman expanded state with a larger radial extension into a compressed statewith a smaller radial extension. This transfer is provided in particularbefore the insertion and removal of the pump into and from the body,since the reduced diameter of the pump housing facilitates thenavigation of the distal end of the pump within the human body and inparticular ensures a minimally invasive passage through the skin. Thepump housing is usually made here from a metal, for example amemory-shape metal. Further materials can be used for the pump housing,provided they withstand the mechanical stresses during the compressionand the expansion and also meet the medical hygiene standards.

In the case of pumps of this type it is also not unusual for theconveying element, such as a rotor, to comprise at least one foldable orflexible segment, for example in the form of a rotor blade. An exampleof a rotor of this type is explained for example in U.S. Ser. No.13/261,565, of which the disclosure is incorporated in its entire scopeinto this application. Furthermore, U.S. Ser. No. 13/261,100 is likewiseincorporated in its entire scope into this application.

With regard to the pump housing, reference is made by way of example toU.S. Ser. No. 13/146,452, which likewise is incorporated in its entirescope into this application. Reference is also made to U.S. Ser. No.13/261,256, which is likewise incorporated in its entire scope into thisapplication.

When designing the pump housing, it has proven to be possible to createa portion which in the expanded state of the pump housing winds along alongitudinal axis extending along the driveshaft, around thislongitudinal axis as considered from the proximal towards the distal endof the pump, in a spiralled manner around the longitudinal axis. Here,however, a structure extending in a spiralled or helical manner, inparticular a spiralled or helical strut, is not to be understood to meanthat this must completely surround the longitudinal axis. It is alsounderstood to mean portions of a spiral which form merely a segment of aspiral around the longitudinal axis, i.e. reference may also be made toa curved strut which substantially follows a course of a spiral aroundthe longitudinal axis over a portion.

With the development of pumps of this type the inventors have identifiedthat an advantageous cooperation between the pump housing, thedriveshaft and the conveying element is helpful in order to create anefficient blood pump that can be implanted over a relatively long periodof time.

This object is achieved by means of a pump according to the features ofClaim 1, according to the features of Claim 14 and according to thefeatures of Claim 15.

In accordance with a first aspect of the invention, the structuresextending helically or a structure (singular) extending helically are/isformed in such a way that when the pump housing is transferred from theexpanded state into the compressed state a torque directed against afirst direction acts on the foldable segment. Here, it should bementioned that in this application reference is made frequently to atorque acting in a clockwise direction or anticlockwise. Morespecifically, reference is not made here to the torque, but to thedirection of the force generating the torque. The torque is the vectorproduct from the radial position vector directed outwardly from alongitudinal axis and the generating force and thus extendsperpendicularly to the generating force. In other words, where referenceis made to a torque extending in a clockwise direction, this rathermeans a torque extending parallel to the longitudinal axis. For the sakeof simplicity and improved orientation, however, the direction of thetorque is often equated with the direction of the generating force,although this does not correspond to the physical definition.

The portion that comprises the structures extending helically preferablyforms merely a limited portion of the pump housing. This portion causesthe pump housing to develop a torque when drawn into the cannula, whichtorque is directed against the direction of the helical winding. Therotor, on account of its form and its flexible or foldable segments, hasa tendency to wrap around the driveshaft in a certain direction uponcompression of the housing. Since the torque is produced uponcompression of the housing, this may likewise act on the foldablesegment and therefore urge the foldable segment for example in a foldingdirection predetermined therefor.

This means that the torque applied by the pump housing assists thenatural folding of the flexible segment around the driveshaft and thuscounteracts damage at the rotor.

In a first embodiment of the first aspect the foldable segment of theconveying element is formed in such a way that the torque of arotational direction of the conveying element is equivalent to theconveyance of a fluid from the distal to the proximal end of the pump.In other words the first direction, in which the helical structuresextend, is opposite to the rotation of the conveying element inoperation when the fluid is conveyed from the distal to the proximal endof the pump when the flexible segments of the conveying element areformed accordingly. Astonishingly, it has been found that both animprovement of the efficiency of the pump is possible as a result, andpotential damage of the pump housing can be reduced.

In a further embodiment the foldable segment of the conveying element iscreated in such a way that the torque is directed opposite to arotational direction of the conveying element, and in addition theunfolding direction of the at least one foldable segment during theunfolding extends in the first direction. This means that the rotationaldirection of the conveying element when conveying the fluid from thedistal to the proximal end is directed opposite to the unfoldingdirection of the rotor.

In a further variant the foldable segment of the conveying element maybe formed in such a way that the torque is directed opposite to arotational direction of the conveying element for conveying a fluid fromthe distal to the proximal end of the pump.

In a further embodiment the unfolding direction of the at least onefoldable segment during unfolding is in a direction opposite to thefirst direction.

In a further embodiment the pump housing is produced from a memory-shapematerial. Here, the pump housing may be manufactured for example fromnitinol.

In a further embodiment the “austenite finish” (A_(f)) temperature ofthe pump housing lies below the body temperature of a healthy human, inparticular below 30° C. and in particular below room temperature, i.e.below 20° C. It has surprisingly been found that at this A_(f)temperature the stability and the longevity of the housing can beimproved. This is true in particular when the A_(f) temperature is belowroom temperature.

In a further embodiment the pump housing comprises a pump-receivingportion and a proximal portion arranged proximally of the pump-receivingportion, wherein an inner diameter of the proximal portion is reducedfrom a diameter of the pump-receiving portion in the expanded state ofthe pump housing to a proximal end of the proximal portion. By means ofa pump housing of this type the drawing into the cannula is facilitatedand assisted on account of the form of the pump housing. Here, a variantof the pump according to the invention is provided in which the helicalstructures are arranged in the proximal portion.

In an alternative embodiment the helical structures are arranged in thepump-receiving portion. In a further embodiment the helical structuresare arranged both in the proximal and in the pump-receiving portion.

In a further embodiment the pump housing comprises a further, distalportion arranged distally of the pump-receiving portion, the innerdiameter of said further, distal portion preferably being reduced from adiameter of the pump-receiving portion in the expanded state of the pumphousing to a distal end of the distal portion.

An improved protection of the rotor is thus possible, since thedriveshaft can be pivoted for example in the region of the reduced innerdiameter of the distal portion by a further bearing.

In a further embodiment the helical structures are also arranged in thedistal portion. Here, the helical structures can be wrapped or woundagainst the first direction. In this embodiment the helical structuresassist the formation of a torque both in the proximal and in the distalportion, said formation of a torque being initiated over the entire pumphousing between the proximal and distal portion, but the torque causinga deflection or twisting of the helical elements merely in the region ofthe proximal and distal portion. In a variant the helical structures inthe proximal and distal region are formed in such a way that the torqueis directed in the same direction proximally and distally and/or theproximal and distal torque is of identical magnitude. This is comparablein an analogy with the wrapping of a sweet in a sweet wrapper, whereinthe sweet can be unwrapped from the wrapper by holding and at the sametime pulling both ends. By way of example, the driveshaft is thusprevented from twisting and the driveshaft is thus protected againstdamage.

In a further embodiment the driveshaft is pivoted alternatively oradditionally in a region of a proximal end of the pump housing.

In a second aspect of the invention an unfolding direction of the atleast one flexible element when transferring the pump housing from thecompressed into the expanded state is provided against the rotationaldirection of the conveying element when a fluid is conveyed from thedistal to the proximal end of the pump, irrespective of helicalstructures. In this case, as in the first aspect of the invention, themovement of the outer end of the segment of the conveying element, asconsidered radially, is to be understood to mean the unfoldingdirection.

A further aspect of the invention comprises a pump housing, a driveshaftarranged in an interior of the pump housing along a longitudinal axis,and a conveying element arranged on the driveshaft. The pump housingcomprises at least one pump-receiving portion and a proximal portionarranged proximally of the pump-receiving portion, wherein the pumphousing can be transferred in a radial direction extending transverselyto the longitudinal direction from a compressed state into an expandedstate. The driveshaft is pivoted in the region of the proximal end ofthe pump housing in a proximal bearing.

In this third aspect of the invention the driveshaft is configured insuch a way that a bending resistance of the driveshaft in the region ofthe proximal portion of the pump housing and distally of the proximalbearing corresponds with a bending resistance of the proximal portion ofthe pump housing. In this way, in the event of any bending, the pumphousing and the conveying element are mounted/pivoted substantiallyconcentrically with one another within the pump-receiving portion. Inother words the bending line of the pump housing in the proximal portionis harmonised with the bending line of the flexible shaft in the regionof the proximal portion, such that a bending moment acting on the distalend of the pump housing induces a similar bend both in the housing andin the shaft. The rotor is thus prevented from colliding with the pumphousing on account of different resistances to bending, and destructionof the pump housing or of the rotor itself is also prevented. During theoperation of the pump, the movement of the beating heart or of thepatient may result in bending moments or forces which may lead, withoutcoordination of the resistances to bending or bending moments, to damageto the rotor or pump housing.

In a variant the bending resistance of the proximal portion of the pumphousing is softer compared with the pump-receiving portion. In theregion of the proximal portion the flexible shaft is also softercompared with a shaft portion in the pump-receiving portion of thehousing.

The bending resistance of the pump housing in the proximal portion maybe influenced for example by helical structures. Due to the helicalstructures, a resilient region which intercepts the mechanicalalternating loads on account of differently acting bending moments iscreated in one exemplary embodiment. Here, in accordance with a variant,the helical structures are to be arranged symmetrically around thelongitudinal axis. The helical structures in this way form a helicalregion which has a spring effect. This spring effect allows the controlof the desired bending resistance. In particular, the desired bendingresistance can be set via the angle or the spiral course of the helicalstructures. In order to ensure a fatigue strength of the pump housing, amaximum local distortion at any point of the pump housing is less than2% in a variant.

In a further embodiment the pump housing also comprises a distal portiondistally of the pump-receiving portion, wherein the driveshaft in theregion of the distal end of the pump housing is pivoted in a distalbearing and a bending resistance of the driveshaft in the region of thedistal portion and proximally of the distal portion is coordinated insuch a way with a bending resistance of the distal portion that when thepump housing bends the conveying element is arranged substantiallyconcentrically within the pump-receiving portion. Here, the driveshaftfor example may additionally be pivoted in the region of the distal endof the pump, such that the driveshaft is fixed between a proximal and adistal bearing. Because the driveshaft in the region of the distal andproximal portion of the pump housing has a bending resistance thatcorresponds with a bending resistance of the pump housing in theproximal or distal portion, it is possible to ensure the substantiallyconcentric mounting of the rotor in the pump housing.

In a further embodiment the pump housing is formed in such a way that itis coordinated with a rigidity of a catheter, for example in the distalor proximal end of the pump region. If the catheter is too rigid, strongdeformations are introduced into the pump housing, however if thecatheter is too soft the position of the housing during operation is notsecured, such that in neither case can reliable operation of the rotorin the pump housing be ensured. By coordinating the rigidity of the pumphousing with the rigidity of the catheter, the concentric mounting ofthe rotor in the pump-receiving portion is ensured here even duringoperation of the pump.

In order to influence the bending resistance of the shaft, a hollowshaft may be used inter alia, which is provided in the region of thepump-receiving portion with a core. In addition, the core may extend asfar as the distal bearing and the proximal bearing.

In the pump arrangements described in this application differentexternal force effects and bending alternating loads act in reality onthe driveshaft, the pump housing, a pigtail arranged distally of thepump housing, and where applicable on bearing elements of the catheteror of the blood pump arrangement. External force effects and bendingalternating loads can be transferred to the catheter for example by aninner wall of the heart, against which the catheter may be abutted orsupported (for example via what is known as a pigtail tip), by pulsatilepressure changes or flow changes of the blood within a heart chamber ora blood vessel, such as the left or right ventricle or the aorta, and/orby a change in position or posture of the body, in particular by a torsomovement or a (leg) movement in the vicinity of a puncture site. Inspite of these loads, blood can be conveyed with the proposed catheterand the proposed blood pump arrangement over relatively long periods oftime, for example over hours, days or even weeks, even at highrotational speeds of the pump rotor, for example in the above-mentionedrotational speed range, for example as in the above-described use of theblood pump arrangement.

It is noted that the features specified in the claims dependent onindependent Claim 1 can also be combined with the second and thirdaspect of the invention.

Further aspects will be explained on the basis of the following figures.

In the figures:

FIG. 1 shows a schematic overview of a pump arrangement;

FIG. 2a to 2d show a variant of a pump housing with conveying elementarranged therein on a driveshaft, which is pivoted merely proximally;

FIG. 3a to 3d show a variant of a pump with a pump housing and aconveying element mounted on a driveshaft, wherein the driveshaft ispivoted distally and proximally;

FIGS. 4a and 4b show an exemplary embodiment of a corresponding bendingresistance between pump housing and driveshaft;

FIGS. 5a and 5b show further embodiments of a pump housing and adriveshaft with corresponding bending resistances;

FIGS. 6a and 6b show embodiments of a driveshaft with core and rotor;

FIG. 7a to 7c show embodiments of a pump housing;

FIG. 8 shows an embodiment of a distal end of the pump housing withcatheter attached therein;

FIG. 9 shows an illustration of a pump arrangement with a coordinatedcombination of pump housing and driveshaft for harmonisation of thebending line.

A schematic overview of a pump arrangement 1 is provided on the basis ofFIG. 1. The pump arrangement 1 comprises a pump housing 2 with a cannulaor a catheter 3, in which a driveshaft 4 is arranged. A conveyingelement 5, which is driven via the driveshaft 4 with a motor 6 attachedat the proximal end of the driveshaft, is located in the region of thepump housing 2. The pump including the driveshaft 4 is introduced herevia a port 7, for example through the femoral artery 8 and the aorticarch 9, into a heart ventricle 10, such that the pump housing to comesto lie in the region of the aortic valve. The rotor 5 is formed here insuch a way that blood is conveyed in the direction 12 from the ventricleinto the aorta, i.e. from the distal end of the pump to the proximal endof the pump.

Various interactions between the housing, the driveshaft, the conveyingelement and the cannula will be explained on the basis of FIG. 2a to 2d. In FIGS. 2a and 2c the pump housing 20 is illustrated in longitudinalsection in the expanded state (FIG. 2a ) and the compressed state (FIG.2c ). Corresponding cross sections can be found in FIGS. 2b and 2 d.

The driveshaft 21 is arranged in the pump housing 20 with the conveyingelement 22 located on the driveshaft. In the present example theconveying element comprises two flexible segments 23 and 24, which areembodied as rotor blades. The pump housing 20 transfers from theexpanded state into the compressed state by pulling the driveshaft inthe pulling direction 25, which is parallel to the longitudinaldirection 26 of the pump housing. A cross section is illustrated in FIG.2b for illustration of the pump housing in the illustration of FIG. 2a .It can be seen that the pump housing 20 is arranged substantiallyconcentrically around the driveshaft 21. In the section illustratedhere, the struts 27 extending helically as helical structures can beseen and widen from the proximal to the distal portion in the radialdirection 27 a. The struts extend from the proximal end of the pumphousing 28 to the distal end of the pump housing 29, in an anticlockwisedirection. By comparison, the conveying element 22 is also shown, ofwhich the flexible segments convey the fluid. This can also be seen inthe plan view of FIG. 2a . Alternatively to the multiplicity of struts,another helical structure may also be selected, for example amultiplicity of struts that form a helical line, i.e. structure, onaccount of their arrangement.

If the pump housing 20 is now drawn into the cannula 30 from theexpanded state illustrated in FIG. 2a into the compressed state bypulling in the pulling direction 25, the helical elements produce atorque 31, which acts in the clockwise direction. It is thus opposed inthe course of the helical struts and attempts to counteract the twistingof the helical struts, although no visible change of the housing isdiscernible. As a result of the torque, the segments 23 and 24 are actedon such that the segments 23 and 24, as illustrated in FIG. 2d , wraparound the driveshaft 21 in the folding direction 32 with the torque 31.Accordingly, the rotor unfolds as the pump housing is slid out from thecannula 30 in the longitudinal direction in the unfolding direction 33.

In the example illustrated here the subsequent rotational direction ofthe rotor is in the rotational direction 34, which is opposite to theunfolding direction. A further unfolding of the rotor at higherrotational speeds can be provided as a result, inter alia. In othervariants, however, it is possible to select the rotational direction tobe consistent with the unfolding direction. A higher rotational speedhere causes an easy folding of the rotor in the folding direction 32.

In the present example the driveshaft is made of a nickel-cobalt alloy,such as 35NL T®, or MP35N®. The cannula is for example formed from acatheter made of a material known from the prior art, such as siliconeor polyurethane. The pump housing may be fabricated for example fromnitinol. Here, in the present example the A_(f) temperature of the pumphousing lies at approximately 150, such that the A_(f) temperature liesbelow room temperature. This has advantages in terms of the stability ofthe pump housing. In the following example the driveshaft is pivotedmerely by a proximal bearing sleeve 35. With regard to the usedmaterials for the rotor, the materials described in U.S. Ser. No.13/261,565 can be used, for example.

In the example illustrated in FIG. 2 the struts arranged helicallyextend both in the proximal portion of the pump housing, which liesproximally of the conveying element 22, and in the region of thepump-receiving portion, which lies in the region of the conveyingelement 22.

A variant of a combination of pump housing, conveying element anddriveshaft is shown by way of example in FIG. 3a to 3 d.

A difference between the embodiments of FIG. 2 and FIG. 3 is, interalia, that the driveshaft in the embodiment of FIG. 3 is pivoted both ina distal end and in the region of a proximal end of the pump housing.

The pump housing 40 illustrated in FIG. 3a comprises a pump-receivingportion 41, a portion 42 arranged distally of the pump-receivingportion, and a distal end portion 43 arranged distally of the distalportion. The pump housing also comprises a proximal portion 44 arrangedproximally of the pump-receiving portion and an end portion 45 arrangedproximally of the proximal portion. The pump housing 40 has, in theproximal portion 44 and the distal portion 42, helical struts 46, whichare shown by way of example in FIG. 3b . The struts extend here from theproximal end of the pump to the distal end of the pump, in ananticlockwise direction. A cannula 47 is additionally shown in FIG. 3a ,which cannula encases the driveshaft 48 as it passes through the aorticarch and the bodily vessels. A rotor 49 is additionally arranged on thedriveshaft in the region of the pump-receiving portion 41 of the housingand serves to convey blood from the distal to the proximal end. It canbe seen on the basis of FIG. 3b that the helical struts 46 extend in theproximal portion 44 in an anticlockwise direction and from the inside(i.e. the distal end of the end portion 45) out (i.e. towards theproximal end of the portion 41), whereas the helical struts 50 in thedistal portion 42 extend in a clockwise direction and from the outsidein. As a result, when the distal end portion 43 and the proximal endportion 45 are grasped and pulled at both portions in oppositedirections, a torque extending in a clockwise direction acts on thepump-receiving portion 41. This mechanism is effective also when thepump housing is drawn into the cannula. In a manner corresponding toFIG. 2a , the pump in FIG. 3a is illustrated in the expanded state. If atensile force 53 directed against the longitudinal direction 52 is noweffective, the diameter of the pump housing is reduced on the one handin the portions 41, 42 and 44, and at the same time the torque 51 actingin a clockwise direction is induced. On account of the reduction of thediameter during the collapse, the pump housing 40 interacts with theconveying element 49 or flexible segments 54 and 55 thereof. On accountof their form and their orientation, the flexible segments 54 and 55have a folding direction 56 in the direction of the torque. In this way,the flexible segments 54 and 55 are wound around the driveshaft 48 inthe folding direction 56. If the pump housing is now transferred fromthe compressed configurations in FIG. 3c into the expanded configurationof FIG. 3a , the rotor unfolds in the unfolding direction 57, whichcoincides with the spiral direction 58 of the helical struts. In thepresent example the rotor 48 then turns in the direction 59 in order toguide the blood from the distal to the proximal end of the pump.

The embodiment shown in FIG. 3 corresponds to a “sweet wrapping”, sincethe spirals defining the course of the helical struts rotate in oppositedirections in the distal and in the proximal portion. As a result atorque is introduced in the pump-receiving portion 41 merely in thedistal and proximal portion 42 and 44, however the torque acting in thedistal and proximal end portions 43 and 45 is reduced. Since bearings(not illustrated) for the driveshaft 48 are located in the distal andproximal end portions, the torque of the pump housing is transmittedwhere appropriate to the driveshaft when the pump housing 40 istransferred from the expanded into the compressed state.

The aspects of the corresponding bending resistance of the pump housingand of the shaft will be discussed on the basis of FIGS. 4a and 4b andalso FIGS. 5a and 5 b.

A pump arrangement corresponding to that of FIG. 3 is illustrated inFIGS. 4a and 4b . In particular, the pump housing 40 comprises theportions 41 to 45 described with reference to FIG. 3, and a driveshaft48, which is held proximally in a first bearing 60 and a distal bearing61. Helical struts 46 and 50 are disposed in the distal and proximalportions 42 and 44 respectively. If a bending moment is now applied tothe pump housing 40, as illustrated in FIG. 4b , the helical struts 46and 50 cause, inter alia, the pump housing to bend on account of theirsymmetrical arrangement around the driveshaft, said bendingcorresponding to a corresponding bending of the driveshaft in the distaland proximal portions 42 and 44 respectively. Here, the shaft may besofter for example in the aforementioned regions than in the region ofthe pump-receiving portion 41. The stiffening in the pump-receivingportion is additionally reinforced by the rotor itself or the rotor hub.As a result, as can be seen in FIG. 4b , the conveying element 49remains substantially concentric within the pump-receiving portion, evenunder bending loads. By way of example on account of the thickness ofthe struts, the selected angle of the helical struts, and also thenumber and arrangement of the struts, a corresponding bending moment canbe adapted to the bending resistance of the shaft in the correspondingregion. Here, the bending moment is the sum of the product from thegenerating force and the corresponding force arm over all acting forces.Here, the force arm is the distance from a bearing point. By way ofexample, a point in the region of the proximal bearing may be selectedas bearing point.

In FIGS. 5a and 5b a corresponding situation is illustrated, wherein thepump arrangement here corresponds substantially to the pump arrangementof FIG. 2. However, the pump housing 20′ in this case has a rigid,pump-receiving portion and a distal portion 201 disposed distally of apump-receiving portion 200, which distal portion has helical structures27. The helical structures 27, which may be generated on account of aconductor-like arrangement of a multiplicity of struts and connectionsthereof or by segmental rotation of strut structures, are configured insuch a way that the bending resistance of the pump housing in the distalportion 201 is softer than in the pump-receiving portion 202. Bendingmoments acting on the pigtail 36 can thus also be absorbed by the distalportion in addition to the distal transition structure 37, which forexample may be constructed from 4 struts.

The bending moment 38 (FIG. 5b ) thus does not act on the pump-receivingportion, such that the driveshaft lies substantially concentricallywithin the pump-receiving portion, even when bending moments areapplied. The pump-receiving portion 200 is more rigid, wherein measuresfor increasing the bending resistance will be explained in one of thesubsequent exemplary embodiments.

The pump housing may optionally also comprise a proximal portion 202having helical structures 27 in order to compensate for an effectivebending moment and in order to facilitate the compression of the pumphousing.

Further details of the various aspects of the invention will bediscussed on the basis of FIGS. 6a and 6b . The shaft arrangement 70comprises the driveshaft 71 with a distal end 72, a conveying element73, and a proximal end 74, which for example can be coupled to a motorusing a coupling element. In the region of the conveying element 73, thedriveshaft 71 is reinforced by a core 75, wherein the core extendsbetween the distal end 72 and a region proximally of the conveyingelement 73. The conveying element 73 comprises two flexible segments 76and 77, which cause a fluid to be conveyed from the distal to theproximal end with a rotational direction of the conveying element in aclockwise direction, as considered from the proximal to the distal end.In FIG. 6b a cross section of the rotor 73 from the proximal end to thedistal end is illustrated. Here, the form of the flexible segments 76and 77 can be seen in greater detail. The folding direction of the rotorwhen the pump housing (not illustrated) is drawn into the cannula is ina clockwise direction, i.e. the points 78 and 79 are transportedradially inwardly and in a clockwise direction. Accordingly, the rotorunfolds as the conveying element is slid out from the catheter in ananticlockwise direction. Therefore, in a variant, the illustratedconveying element or the shaft arrangement 70 is provided with a housingformed in such a way that this produces a torque in a clockwisedirection when the pump housing is transferred from the expanded intothe compressed state.

Here, the core 75 may produce an improved rigidity compared with theother regions of the hollow driveshaft 71. Here, the core may havedifferent rigidities from its distal to its proximal end, such that forexample the bending resistance proximally and/or distally of theconveying element is reduced compared with the rigidity of the core inthe region of the conveying element. The corresponding rigidity of theshaft in the region of the conveying element, however, may also beachieved by a corresponding design (or coordination) of the rotor hub.

Further details of a pump housing will be explained on the basis of FIG.7a to 7c . In FIG. 7a the pump housing illustrated in FIG. 7b has beencut along a fictitious separation line, unrolled and pressed flat.However, in one embodiment the pump housing, as illustrated in FIG. 7a ,is first cut out for example by means of a laser. Here, the cutting-outcan be performed within a tube mould. The form illustrated in FIG. 7b isthen provided by means of an annealing process in a mould. The pumphousing 80 in FIG. 7a , likewise unrolled, has at its proximal end 81the proximal end portion 83, which extends as far as the helicalelements 82. A short region before and after the helical struts 82 heredefines the proximal portion 84. The pump-receiving portion 85 has alattice design, in which the struts interconnected in a lattice shapehave points of contact with one another. Similarly to the proximalportion 84, the distal portion 86 has helical struts 87, which areobviously directed to the struts 82 in terms of their spiral direction.At the distal end there is disposed a distal end portion 88, in theregion of which for example the driveshaft can be pivoted in a catheteror pigtail. The angle at which the helical elements 82 extend from theproximal end portion to the pump-receiving portion may be between 20 and40°, for example. Similarly, the angle of the struts 87 may also be 20to 40° (but in the opposite direction).

In their embodiment, the two angles are oppositely directed, asillustrated in FIG. 7. If the pump housing 80 is now joined together, asindicated above, the pump housing in the expanded state as illustratedin FIG. 7b is produced. It can be clearly seen that in the region of theproximal and distal portions 84 and 86 respectively there is a wideningof the inner diameter from the proximal to the distal end and viceversa. The pump-receiving portion 85 here has the greatest innerdiameter in order to attain a high efficiency when conveying the fluid.A cross section of the pump housing 80, as considered from the proximalend to the distal end, is shown in FIG. 7c , wherein it can be clearlyseen that the struts 82 run in an anticlockwise direction. Thesupporting struts 89 are also illustrated and transition to the latticestruts 85 a of the pump-receiving portion.

The distal end portion 88 of the pump housing 80 is illustrated on thebasis of FIG. 8. Here, a catheter 90 is inserted into the distal endportion 88 and comprises, inter alia, a bearing sleeve 91, in which thedistal end of the shaft arrangement 70 is pivoted. Here, the bearing mayconsist for example of a ceramic, whereas the shaft may be constructedfrom the previously described materials.

In FIG. 9 a longitudinal section through a pump arrangement 100 isshown, which comprises a pump housing 101, a driveshaft 102, and a rotor103 arranged on the driveshaft. An outflow tube 104 is also illustrated.In the distal end region 110 of the pump housing, this is connected to acatheter formed as a pigtail (not illustrated). Here, the mounting ofthe driveshaft 102 in the distal end portion corresponds substantiallyto the mounting explained on the basis of FIG. 8.

In the region of the proximal end portion 111 there is disposed aproximal bearing/pivoting 112 of the driveshaft, which comprises both aradial bearing and an axial bearing. This bearing is explained ingreater detail in the European patent application published as EP2868289 A1 (having the internal file reference 137EP 2457). Thatapplication is incorporated fully into this application.

Between the distal and proximal end portions of the pump housing 101there are disposed the distal portion 112, the pump-receiving portion113, and the proximal portion 114. Here, both the distal and theproximal portion have helical struts 115 and 116 respectively, whichtransition towards the pump-receiving portion into supporting struts 117and 118 respectively. These supporting struts each split further intostruts 119 of the pump-receiving portion. On the inner side of thepump-receiving portion there is located a plastics film 120, which isproduced in an exemplary embodiment from a polyurethane. This filmimproves the conveying effect of the rotor 103.

The rotor 103 comprises two flexible rotor blades 130 and 131, which arefastened to a hub 132. In some exemplary embodiments the rotor is asingle workpiece made of a plastic, such as polyurethane, for examplebiresin, or from a silicone or Pebax. For reasons of clarity, the rotor103 is not shown in a longitudinal sectional illustration.

The rotor 103 is arranged on a driveshaft 102, which is formed as ahollow shaft. Reference is made to the application PMP Ref. 137EP 2457with regard to further details. The hollow shaft is reinforced by a core105 between the distal and proximal bearing/pivoting.

When coordinating the bending line of the pump housing with the bendingline of the driveshaft, it should be ensured, in the event of a bendingmoment 140 (or 141 or 142) acting on the pump housing, that the rotor103 remains substantially concentric in the pump-receiving portion 113,or that the rotor does not contact the inner face of the pump-receivingportion 113. As a first measure the bending resistance of thepump-receiving portion is more rigid in this exemplary embodiment thanthe bending resistance of the distal or proximal portion. For the sakeof simplicity, the bending resistances of the distal and proximalportion are selected symmetrically in the shown exemplary embodiment. Apossibility to influence the bending resistance in the pump-receivingportion 113 is constituted by the density and number of the struts 119in relation to the considered diameter of the housing.

In the present example the distal and proximal portions 112 and 114respectively each have 10 helical struts, which transition into 20supporting struts 117 and 118 respectively towards the pump-receivingportion. The supporting struts 117 and 118 split again into 40 struts119, such that the number of struts in the pump-receiving region isgreater here by a factor of 4. In other exemplary embodiments thisfactor may vary between 0.9 and 20. The bending resistance in thepump-receiving portion is in this way greater than in the distal orproximal region.

A further possibility for matching (here: making softer) the bendingresistances of the distal and proximal portion compared with thepump-receiving portion is constituted by the change of the geometricdimensions of the struts 115-119. In the present example the struts 115and 116 are thicker by a factor of 2 to 3 than the struts 119. Onaccount of the factor 4 in the ratio of the number of struts, theproximal and distal portion would otherwise be too soft in someexemplary embodiments if the struts 115-119 were of equal thickness.

A further possibility for matching the bending resistance in the regionof the proximal and distal portions is constituted by the selection ofthe bending angle of the helical struts. In the present example thehelical struts wind by an angle of approximately 30° from the distal tothe proximal end of the proximal or distal portion. However, the rangemay also lie in a range from 5° to 90°.

A further possibility is to vary the length of the proximal and distalportion. In a method for matching the bending resistance of the pumphousing, the shaft arrangement is first measured, and theabove-mentioned parameters of the different portions of the pump housingare then calculated, and a suitable pump housing is then produced.

The bending resistance of the driveshaft may be matched by the rigidityof the hollow shaft, of the core and of the rotor. Since the hollowshaft in some exemplary embodiments may be exposed to strong curvatures,for example in the aortic arch, the hollow shaft must have a bendingresistance that allows a curvature of this type and at the same time hasa strength so as to be able to operate for as long as possible at highrotational speeds. In some exemplary embodiments the bending resistanceof the hollow shaft is therefore adapted primarily to the requirementsof the hollow shaft between motor and bearing. However, the rigidity ofthe core may also be adapted in order to adapt the bending line of thedriveshaft to the bending resistance of the pump housing between theproximal and distal bearing.

Furthermore, the material selection and geometry of the rotor 103 causesa stiffening of the driveshaft in the region of the pump-receivingportion 113, such that the driveshaft arrangement with rotor is softerin the region of the distal and proximal portion than in the region ofthe pump-receiving portion. Further adaptation possibilities will becomeclear to a person skilled in the art from the comments made here.

In a further exemplary embodiment the pump housing has a helicalstructure, which occurs as a result of a multiplicity of interconnectedstruts. Due to the selection of the connection point between two struts,although the struts extend at an incline upwardly or downwardly, ahelical structure directed in one direction is produced. The bendingresistance of this structure may be matched to the bending resistance ofthe driveshaft by changes to the thickness, number and length of thestructure and by changes to the encompassed angle of the structure.

Further embodiments and variants of the invention will emerge from thecombinations specified here and from the combinations apparent to aperson skilled in the art.

1-20. (canceled)
 21. A pump, in particular a blood pump, comprising: apump housing having a proximal end, a distal end, a region of theproximal end, and a region of the distal end, a driveshaft arranged inan interior of the pump housing along a longitudinal axis; and aconveying element arranged on the driveshaft, wherein the pump housingcomprises at least one pump-receiving portion and a proximal portionarranged proximally of the pump-receiving portion, and can betransferred in a radial direction extending transversely to thelongitudinal direction from a compressed state into an expanded state;and wherein the driveshaft is pivotable on a proximal bearing, theproximal bearing located in the region of the proximal end of the pumphousing, wherein the driveshaft is configured in such a way that abending resistance of the driveshaft in a region of the proximal portionof the pump housing and distal of the proximal bearing is coordinatedwith a bending resistance of the proximal portion, such that when thepump housing bends the conveying element is arranged substantiallyconcentrically within the pump-receiving portion.
 22. The pump accordingto claim 21, wherein the conveying element comprises at least onefoldable segment, wherein the at least one foldable segment isconfigured to collapse in response to an application of a torque. 23.The pump according to claim 21, wherein the pump housing also comprisesa distal portion arranged distally of the pump-receiving portion,wherein the driveshaft is pivotable in the region of the distal end ofthe pump housing in a distal bearing, and a bending resistance of thedriveshaft in a region of the distal portion and proximal of the distalportion is coordinated with a bending resistance of the distal portionin such a way that when the pump housing bends the conveying element isarranged substantially concentrically within the pump-receiving portion.24. The pump according to claim 21, wherein the bending resistance ofthe proximal portion is determined substantially by a bending resistanceof helical struts extending along the longitudinal axis, wherein thedriveshaft is pivotable on a distal bearing, the distal bearing locatedin a distal portion arranged distal of the pump-receiving portion of thepump housing, and a bending resistance of the driveshaft in a region ofthe distal portion and proximal of the distal portion is coordinatedwith a bending resistance of the distal portion in such a way that whenthe pump housing bends the conveying element is arranged substantiallyconcentrically within the pump-receiving portion and the bendingresistance of the distal portion is determined substantially by thebending resistance of helical struts extending along the longitudinalaxis.
 25. The pump according to claim 21, wherein the driveshaft is ahollow shaft which comprises a core in the region of the pump housing.26. The pump according to claim 21, wherein an Austenite finishtemperature of the pump housing lies below a temperature of 34° C. 27.The pump according to claim 26, wherein the Austenite finish temperatureof the pump housing lies below a temperature of 30° C.
 28. The pumpaccording to claim 27, wherein the Austenite finish temperature of thepump housing lies below a temperature of 20° C.
 29. The pump accordingto claim 21, wherein the driveshaft comprises a nickel-cobalt alloy. 30.A pump, in particular a blood pump, comprising: a proximal end and adistal end and a pump housing arranged therebetween, a driveshaftarranged in an interior of the pump housing along a longitudinaldirection, and a conveying element arranged on the driveshaft, whereinthe conveying element comprises at least one foldable segment, theconveying element configured such that that a rotational direction ofthe conveying element causes a fluid to be conveyed from the distal endto the proximal end of the pump; wherein the pump housing is configuredsuch that the pump housing can be transferred at least in part into acannula under application of a force acting at the proximal end of thepump, and in doing so is transferred along a radial direction extendingtransversely to the longitudinal direction from an expanded state into acompressed state; and wherein an unfolding direction of the at least onefoldable segment when the pump housing is transferred from thecompressed into the expanded state is directed against the rotationaldirection.
 31. The pump according to claim 30, wherein the at least onefoldable segment is configured to collapse in response to an applicationof a torque.
 32. The pump according to claim 31, wherein the at leastone foldable segment of the conveying element is formed in such a waythat the torque is directed in a same direction as a rotationaldirection of the conveying element for conveying a fluid from the distalend to the proximal end of the pump.
 33. The pump according to claim 31,wherein the at least one foldable segment of the conveying element isformed in such a way that the torque is directed opposite to a conveyingdirection of the conveying element for conveying a fluid from the distalend to the proximal end of the pump.
 34. The pump according to claim 31,wherein an unfolding direction of the at least one foldable segmentextends in the first direction during the unfolding.
 35. The pumpaccording to claim 31, wherein an unfolding direction of the at leastone foldable segment extends in a direction opposite to the firstdirection during the unfolding.
 36. The pump according to claim 30,wherein the pump housing is produced from a memory-shape material. 37.The pump according to claim 30, wherein the pump housing comprises apump-receiving portion and a proximal portion arranged proximal of thepump-receiving portion, wherein an inner diameter of the proximalportion is reduced from a diameter of the pump-receiving portion in theexpanded state of the pump housing towards a proximal end of theproximal portion.
 38. The pump according to claim 30, wherein thedriveshaft is a hollow shaft which comprises a core in the region of thepump housing.
 39. The pump according to claim 30, wherein the driveshaftis pivotable in a region of a proximal end of the pump housing.
 40. Thepump according to claim 39, wherein the driveshaft is pivotableadditionally in a region of a distal end of the pump housing.